They kep the summer sun out of their houses by using shade trees, climbing vines, and south-facing windows. They knew that windows to the south get very little sunlight in summer but lots in the winter, and key knew that east or west windows dor just the opposite.

the kept hot air out by closing the windows and doors during the day, and by securing real working shuttes across them. They generated as little heat as possible inside the house by cooking outside over a simple pit fireplace.

At night, when outdoor air temperatues dropped, they would open their houses to the cool breezes, and they would, in effect, store up coolness for the next day in the dirt or stone floors and the massive fireplace and chimney. A typical colonial fireplace weighed perhaps fifty tons, and once throughly chilled by a night's fresh winds it could keep the flanking rooms cool throughout a long summer's day.

By the middle of the 19th century, builders were less careful about window orientations, and the stately centrl fireplace had shrunk to a minimal chimney for iron stoves. Houses were correspondingy more difficult to keep cool. But the Victorian builders added some new and interesting summer-comfort twists, such as the easily cross-ventilated bay window, the screened-in sleeping portch, and the breeze-creating swing on the front veranda.

The 20th century brought us such thermal detriments as the picture window which faces any direction so long as it's toward the street, the unscreened deck or patio whose usefulness is destroyed by biting insects for much of the summer, and the unventilated attic. It also brought us the snarling air conditioner with its piercing drafts and inexcusable energy consumption, a mixed blessing at best.

A family in an ordinary house or apartment in New England today can be comfortable on all but a handful of summer days and nights without the use of mechnaical air conditioning. It simply involves, as it did for our early forebears, the application of some common-sense rules.

* Keep the sun out. Shades, blinds, or curtains aren't much help, because they intercept sunlight after it's already through the glass and inside the hosue. You have to stop sunlight outsidem -- before it gets to the glass -- using big trees, vines, awnings, overhangs, or working shutters. If you're building a new house, make sure the larger windows face south, and put a two-foot roof overhang or projecting trellis a foot or so above each of them. This will create rooms that are sunfilled in winter, but shaded and cool in the summer.

* Keep hot air out. Use good insulation in the attic and walls, and an attic fan or louvers to ventilate above the ceilings. Invest in an indoor/outdoor thermomenter: Whenever it's cooler outdoors than in, open the windows. Whenever it's warmer, close them. Use a portable electric fan to keep the air moving inside the house when the windows are closed.

* Generate as little heat inside the house as possible. Avoid using the oven in hot weather. Cook outdoors when possible. Run appliances such as dishwashers and laundry equipment only at night or on cool days. Keep lights, radios, and televisions turned off except when you are using them. A typical house is heated five degrees or more just by lights and appliances, and this rule can often shave several degrees off inside temperatures.

If you build or remodel a house, try to work in a large fireplace, masonry wall, or ceramic tile floor to store coolness. Be sure every room can cross-ventilate at night. Add a screened portch. Plant plenty of shade trees to the east and west. Finish a basement room and put an electric dehumidifier in it, to provide a cool last-ditch refuge regardless of the weather upstairs.

Do these rules really work? You bet they do, just as they did three centuries ago. With the application of some intelligence and resourcefulness almost any well-insulated house or apartment in New England can be kept comfortable for most days of the summer without air conditioning.

There are, of course, a few August nights when the temperature hangs in the high 80s with humidity to match. Then the above rules won't quite do the job, and you have to resort to the final rule: Take in a double feature at an air-conditioned theater. Hollywood, you see, has known about those August nights for many years now, and has thoughtfully provided the ideal solution.